Simkania negevensis is a Chlamydia-like intracellular microorganism that has been associated with respiratory tract infection in infants and in adults. Exposure to the organism is prevalent in many parts of the world. It can be found in tap water and can grow in free-living amoebae. Impairment of local host defenses and a higher intensity of immunosuppression render lung transplant (LTx) patients uniquely susceptible to infections. We detected S. negevensis DNA in 40/41 bronchoalveolar lavage (BAL) samples from lung transplantation (LTx) patients, but not in BAL from immunocompetent controls. We further studied 19 lung transplants with 51 sequential BALs, using a regression analysis S. negevensis infection was associated with a higher likelihood of developing acute rejection which, however, did not reach statistical significance. The overall aim of this pilot study is to obtain data that will enable preliminary assessment of the need for an extensive prospective study of the involvement of this microorganism in LTx inflammation and rejection. A secondary aim is to develop an in vitro pulmonary epithelial cell model system in which the effect of S. negevensis infection on inflammatory cytokine induction and secretion can be studied. To achieve the main aim, we will examine 195 BAL samples from LTx patients in various clinical conditions (no rejection, acute rejection, chronic rejection) for evidence of S. negevensis infection in order to determine whether pulmonary S. negevensis infection is associated with these conditions. In parallel, Chlamydophila pneumoniae will be monitored as an internal control. The secondary aim will be achieved by study of the fate of the organism in bronchial epithelial cells in vitro, and its ability to induce inflammatory or profibrotic cytokine secretion. We will compare S. negevensis detected in patient specimens using DNA amplification and sequence analyses. Great similarity between organisms detected will justify a preliminary search for a possible common source of infection, i.e., testing tap water samples from the transplantation unit for S. negevensis DNA and comparison to that of organisms detected in patients. [unreadable] [unreadable] [unreadable]